nickm
Joined: 07 Mar 2008
Location: Johannesburg
Posts: 19
 
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| Terrain response setting on dirt |
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What terrain response setting do you guys use for normal SA dirt roads? I've typically been leaving the vehicle on 'normal'. My rationale has been to avoid stress through the drive train from the locked diffs in 'grass gravel snow'. However I've since read that braking performance would improve on the special settings.
Thoughts appreciated.
Nick
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 Thu Apr 17 2008 3:52pm |
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Hobgoblin
Joined: 15 Nov 2007
Location: Shropshire
Posts: 287
 
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My understanding is the diffs are fully electronic and only lock when needed, threfore should not put any extra strain on the drivetrain.
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| Thu Apr 17 2008 4:02pm |
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nickm
Joined: 07 Mar 2008
Location: Johannesburg
Posts: 19
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OK, that's interesting, I had understood the diffs to be permanently locked in the 'Grass/Gravel/Snow' setting.
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| Thu Apr 17 2008 4:34pm |
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caverD3
Joined: 03 Jul 2006
Location: Sydney
Posts: 1516
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IFAIK none of the diffs lock completey it is variable rather than on/off.
I use TR when the road becomes bumpy otherwise, off.
Interesting thought about brakes though, may be callibrated differently for gravel setting.
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| Thu Apr 17 2008 4:43pm |
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nickm
Joined: 07 Mar 2008
Location: Johannesburg
Posts: 19
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My understanding is that the ABS is optimised for different surfaces. For instance, on tar the system releases the brake just before locking is sensed whereas in sand the wheel is actually allowed to lock for a period since the effect of sand forming a ridge in front of the wheel actually reduces stopping distance.
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| Thu Apr 17 2008 4:50pm |
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robharvey
Joined: 14 May 2007
Location: Durban
Posts: 89
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I tend to go the "Grass/Gravel/Snow" route. In my experience although throttle response is diminished, the DSC cuts in earlier preventing the back coming out on tighter corners. I tested the system about a year ago, on very worn GY Wranglers, and was amazed at how the elctronics "pulled" me round the corner, when by rights the back should have overtaken me.
I may be wrong but the diffs shouldn't lock on a normal gravel road, and if they do it will be temporary as they are limited slip diffs and not permanent (he says in tech-speak) 
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| Thu Apr 17 2008 7:06pm |
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nickm
Joined: 07 Mar 2008
Location: Johannesburg
Posts: 19
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Interesting point about DSC. Frankly I have never quite got my head around what DSC does as opposed to traction control. 
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| Fri Apr 18 2008 5:07am |
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WayneD
Joined: 11 Sep 2007
Location: Sydney
Posts: 79
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During a trip last year the wife was driving of the tar doing about 100KPH and went off the shoulder. The DSC kicked in and slowed the vehicle down very quickly while using alternative brakes. A scary situation but the vehicle took control completely and stopped what could have been a roll over situation. The vehicle was loaded for a month in the outback.  The vehicle was 2 weeks old.
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| Fri Apr 18 2008 5:25am |
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caverD3
Joined: 03 Jul 2006
Location: Sydney
Posts: 1516
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A good system to have. That is why safety experts like it, takes over when you do something dumb.
Was the TR on or off?
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| Fri Apr 18 2008 6:23am |
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heine
Joined: 07 Feb 2007
Location: Midrand
Posts: 1359
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I notice a big drop off in power between normal and grass/gravel/snow . But I assume this is also more noticable because of the remap ?
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| Fri Apr 18 2008 8:02am |
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nickm
Joined: 07 Mar 2008
Location: Johannesburg
Posts: 19
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heine, I notice a big drop off in throttle response, but do you actually think there is a drop in power as well? Why would that make sense?
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| Fri Apr 18 2008 1:49pm |
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PaulP
Joined: 04 May 2007
Location: Barcelona
Posts: 537
 
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There's no drop off in power in GGS....the throttle response is just 'softened' meaning that you need to push the pedal further to get the same response from it.....(exactly the opposite to what happens in Sand mode).
In heine's case he will notice a huge difference as his engine re-map will give him loads more go in normal mode (230 bhp?) with no TR mode selected and when he sticks it in GGS, it will use a 'softened' version of the standard engine map (190 bhp).
The diff(s) are, as already mentioned, variably locking...they never physically lock 100% but in some TR modes (such as GGS) they are pre-loaded to come into play much earlier than in standard mode. The TC is also primed to cut wheelsping earlier (GGS, rock crawl) or later (sand) depending on the mode selected.
TC prevents wheels from spinning when they have no traction. Either by cutting power or applying the brakes to the spinning wheel(s) using the ABS module. A wheel is considered to have lost traction when the ABS/wheel speed sensors detect that it's speed is different to the others by a certain degree. Of course, you will often have more than one wheel without traction but you get the idea 
DSC works with the TC system, taking it's data from different sensors (including yaw/pitch and others that I don't understand) to keep the car going where it is pointed or where it should be going.
I hope this helps 
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| Fri Apr 18 2008 4:38pm |
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nickm
Joined: 07 Mar 2008
Location: Johannesburg
Posts: 19
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Thanks PaulP, that does help. Overall my takeaway is that on a 'normal' South African dirt road it probably does make sense to be in GGS, especially if the surface is at all loose.
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| Fri Apr 18 2008 4:53pm |
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Kabous
Joined: 11 Jul 2007
Location: Mokopane
Posts: 43
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I always change the TR setting to GGS when leaving paved roads , it not only readies the vehicle's drive train for loose sand etc. but also softens the ride substantially (airbag suspension). Handles a lot better on gravel/dirt roads in GGS.
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| Fri May 09 2008 10:13am |
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PaulP
Joined: 04 May 2007
Location: Barcelona
Posts: 537
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Kabous wrote:but also softens the ride substantially (airbag suspension).
I don't think it does....I'm 99.999% sure that the D3 can't modify the stiffness of it's suspension in any way.
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| Fri May 09 2008 10:21am |
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